In RF filters which may be contained, e.g., in duplexers, resonators are generally used. The resonators generally have a specific resonant frequency ω0 and a specific antiresonant frequency ωp, at which the impedance of the resonator forms a pole. These two frequencies have a great influence on characteristic filter properties. If resonators are interconnected, e.g., to form bandpass filters, then said frequencies determine the position and width of the passband. Conventional resonators therefore have a limited area of application with regard to their operating frequencies.
Further parameters that determine resonators and hence filters are the power compatibility and the extent to which the filters operate in a sufficiently linear range.